Human urine and extract of urine have been known for some time to contain both pressor and depressor substances. Most substances thus fa studied illicit acute responses and little attention has been giben to more chronic effects. The purpose of this project is to isolate a hypertensive substance from normal human urine, to determine its chemical and physical properties and finally to determine its structure. The hypertensive factor will be islolated by adsorption and elution from benzoic acid and further purified by numerous types of chromatography combined with other methods as found feasible. Those yielding the best resolution will be used for larger scale preparation. The physiological role of this compound will be studied to evaluate its possible role in hypertension. This will be approached by studying (1) the effect of the hypertensive compound on ion transport, plasma volume and extracellula fluid vol; (2) the effect of his compound on renin-angiotensin system.